"Threshold is only 600 ohms. Any CJ, ARC, or Cary run through the RCA inputs will be fine"
I don't think any of the Cary preamps would be a good match based on the impedence issues. The 98 spikes up to 6,800 ohms for its output impedence at 20 Hz. (according to the Stereophile tests).
This is a very low impedence at the Threshold and will make impedence matching very difficult for most preamps. I would do a search as to what others have had success with running their Threshold, particularly questioning the LFE performance. I would automatically be skeptical of anybody saying their bass is great when such an extreme mismatch is so apparently obvious.
I don't think any of the Cary preamps would be a good match based on the impedence issues. The 98 spikes up to 6,800 ohms for its output impedence at 20 Hz. (according to the Stereophile tests).
This is a very low impedence at the Threshold and will make impedence matching very difficult for most preamps. I would do a search as to what others have had success with running their Threshold, particularly questioning the LFE performance. I would automatically be skeptical of anybody saying their bass is great when such an extreme mismatch is so apparently obvious.